Movement before a fall? (4,5)

'movement' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps you can see a link between them that I don't see?

'before a fall?' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'an' and 'an' is located in the answer.
'fall?' could be 'rain' (raining is a kind of falling) and 'rain' is found within the answer.
This explanation may well be incorrect...